US12456938B2ActiveUtilityA1
Brushless permanent magnet motor
Est. expiryFeb 25, 2041(~14.6 yrs left)· nominal 20-yr term from priority
Inventors:Máté Horvát
H02P 21/14H02P 21/0003H02P 6/153H02P 21/22H02P 6/085H02M 7/5395H02M 7/5387H02P 6/182H02P 29/50H02P 27/12H02P 27/08
52
PatentIndex Score
0
Cited by
19
References
19
Claims
Abstract
A brushless permanent magnet motor has a phase winding, an inverter for applying voltage vectors to the phase winding, and a controller for controlling the inverter. The inverter has a plurality of high side switches and a plurality of low side switches. The controller is configured to divide an electrical cycle of the motor into a first portion and a second portion different to the first portion, apply a first set of voltage vectors to the phase winding in the first portion of the electrical cycle, and apply a second set of voltage vectors to the phase winding in the second portion of the electrical cycle. The second set of voltage vectors is different to the first set of voltage vectors. The controller is configured to turn on a low side switch to apply each voltage vector of the first set of voltage vectors, and turn off all low side switches to apply a zero-voltage vector of the second set of voltage vectors.
Claims
exact text as granted — not AI-modifiedThe invention claimed is:
1 . A brushless permanent magnet motor comprising:
a phase winding, an inverter for applying voltage vectors to the phase winding, and a controller for controlling the inverter, wherein the inverter comprises a plurality of high side switches and a plurality of low side switches, and the controller is configured to: divide an electrical cycle of the motor into a first portion and a second portion different to the first portion, apply a first set of voltage vectors to the phase winding in the first portion of the electrical cycle, apply a second set of voltage vectors to the phase winding in the second portion of the electrical cycle, the second set of voltage vectors different to the first set of voltage vectors, in the first portion of the electrical cycle, turn on a low side switch of the plurality of low side switches, to apply each voltage vector of the first set of voltage vectors, in the first portion of the electrical cycle, estimate a position of a rotor of the brushless permanent magnet motor using a determined current value indicative of current flowing through the phase winding, and in the second portion of the electrical cycle, turn off all low side switches to apply a zero-voltage vector of the second set of voltage vectors.
2 . The brushless permanent magnet motor as claimed in claim 1 , wherein the controller is configured to turn on all low side switches to apply a zero-voltage vector of the first set of voltage vectors.
3 . The brushless permanent magnet motor as claimed in claim 1 , wherein the controller is configured to turn on all low side switches to apply a further zero-voltage vector of the second set of voltage vectors.
4 . The brushless permanent magnet motor as claimed in claim 1 , wherein the second set of voltage vectors comprises more voltage vectors than the first set of voltage vectors.
5 . The brushless permanent magnet motor as claimed in claim 1 , wherein the controller is configured to apply the first set of voltage vectors in a first sequence and to apply the second set of voltage vectors in a second sequence, the first sequence comprising a non-zero voltage vector applied at a mid-point of the first sequence, and the second sequence comprising the zero-voltage vector applied at a mid-point of the second sequence.
6 . The brushless permanent magnet motor as claimed in claim 1 , wherein the brushless permanent magnet motor comprises a three-phase brushless permanent magnet motor having three phase windings, and the inverter comprises a three-phase inverter having three high side switches and three low side switches.
7 . The brushless permanent magnet motor as claimed in claim 1 , wherein the controller employs five-step space vector pulse width modulation to apply the first set of voltage vectors in the first portion of the electrical cycle, and employs seven-step space vector pulse width modulation to apply the second set of voltage vectors in the second portion of the electrical cycle.
8 . The brushless permanent magnet motor as claimed in claim 1 , wherein the first portion of the electrical cycle comprises 120 degree of the electrical cycle, and the second portion of the electrical cycle comprises 240 degrees of the electrical cycle.
9 . The brushless permanent magnet motor as claimed in claim 1 , wherein the brushless permanent magnet motor comprises a resistor connected in series with the low side switch turned on to apply each voltage vector of the first set of voltage vectors, and the controller is configured to monitor the voltage across the resistor in the first portion of the electrical cycle to determine the current value indicative of current flowing through the phase winding in the first portion of the electrical cycle using the monitored voltage.
10 . The brushless permanent magnet motor as claimed in claim 1 , wherein the controller is configured to obtain a reference voltage value indicative of a voltage applied to the phase winding of the motor, calculate a phase of back EMF induced in the phase winding using the determined current value and the reference voltage value, determine a zero-crossing point of the back EMF induced in the phase winding using the calculated phase of back EMF induced in the phase winding, and generate a rotor position signal based on the determined zero-crossing point.
11 . The brushless permanent magnet motor as claimed in claim 10 , wherein the phase of back EMF induced in the phase winding is calculated using the equation:
-
E
p
h
X
∝
I
p
h
X
R
p
h
X
+
(
L
s
e
l
f
p
h
X
-
L
m
u
t
u
a
l
p
h
X
)
dI
p
h
X
d
t
-
V
p
h
X
;
where E phX is the back EMF induced in the phase winding X, L selfphX is the self-inductance of the phase winding X, L mutualphX is the s mutual inductance of the phase winding X with other phase windings of the motor, I phX is the current value indicative of current flowing through the phase winding X, R phX is the resistance of the phase winding X, and V phX is the reference voltage value indicative of the voltage applied to the phase winding X.
12 . The brushless permanent magnet motor as claimed in claim 10 , wherein determining a zero-crossing point of the back EMF induced in the phase winding comprises utilising any of a calculated phase of back EMF induced in the phase winding, an amplitude representative of the amplitude of back EMF induced in the phase winding, and a frequency representative of the frequency of back EMF induced in the phase winding.
13 . The brushless permanent magnet motor as claimed in claim 10 , wherein calculating a phase of back EMF induced in the phase winding comprises integrating the equation:
-
E
p
h
X
∝
I
p
h
X
R
p
h
X
+
(
L
s
e
l
f
p
h
X
-
L
m
u
t
u
a
l
p
h
X
)
dI
p
h
X
d
t
-
V
p
h
X
;
to obtain a relationship representative of integrated back EMF.
14 . The brushless permanent magnet motor as claimed in claim 13 , wherein calculating a phase of back EMF induced in the phase winding comprises equating integrated back EMF to an integral of a sinusoidal waveform representative of back EMF induced in the phase winding.
15 . The brushless permanent magnet motor as claimed in claim 10 , wherein the controller is configured to utilise a determined zero-crossing point of back EMF induced in the phase winding to calculate an electrical period of the rotor.
16 . The brushless permanent magnet motor as claimed in claim 10 , wherein the controller is configured to utilise a determined zero-crossing point of back EMF induced in the phase winding to calculate a speed of the rotor.
17 . The brushless permanent magnet motor as claimed in claim 10 , wherein the controller is configured to utilise a determined zero-crossing point of back EMF induced in the phase winding to generate a signal representing continuous position of the rotor.
18 . A method of controlling a brushless permanent magnet motor comprising a phase winding and an inverter for applying voltage vectors to the phase winding, the inverter comprising a plurality of high side switches and a plurality of low side switches, wherein the method comprises:
dividing an electrical cycle of the motor into a first portion and a second portion different to the first portion, applying a first set of voltage vectors to the phase winding in the first portion, applying a second set of voltage vectors to the phase winding in the second portion, the second set of voltage vectors different to the first set of voltage vectors, turning on, in the first portion of the electrical cycle, a low side switch to apply each voltage vector of the first set of voltage vectors, estimating, in the first portion of the electrical cycle, a position of a rotor of the brushless permanent magnet motor using a determined current value indicative of current flowing through the phase winding, and turning off, in the second portion of the electrical cycle, all low side switches to apply at least one voltage vector of the second set of voltage vectors.
19 . A data carrier comprising machine readable instructions for the operation of a controller of a brushless permanent magnet motor to:
divide an electrical cycle of the motor into a first portion and a second portion different to the first portion, apply a first set of voltage vectors to a phase winding of the motor in the first portion, apply a second set of voltage vectors to the phase winding in the second portion, the second set of voltage vectors different to the first set of voltage vectors, in the first portion of the electrical cycle, turn on a low side switch to apply each voltage vector of the first set of voltage vectors, in the first portion of the electrical cycle, estimate a position of a rotor of the brushless permanent magnet motor using a determined current value indicate of current flowing through the phase winding, and in the second portion of the electrical cycle, turn off all low side switches to apply at least one voltage vector of the second set of voltage vectors.Join the waitlist — get patent alerts
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